What are the rituals to be followed by a girl who has recently obtained legal divorce?
Hinduism does not recognize the modern notion and concept of the legal divorce.
So, there are no rituals, because divorce is an alien concept.
Manusmṛti says -
सकृदंशो निपतति सकृत् कन्या प्रदीयते ।
सकृदाह ददानीति त्रीण्येतानि सतां सकृत् ॥ ४७ ॥
- Once does the share fall to a man; once is a maiden given away; once does one say ‘I give’; each of these three comes only once.
Almost all the canonical scriptures concur on this 'doctrine of only one marriage for a women', except in the cases of some exceptional exceptions (for instance, cf. Agni Purāṇa 154. 3-6).